We recently received this ominous-looking cloud, that quite honestly doesn't even look real. But we're here to tell you it very much is.

The cloud pictured above is "Asperitas" or "Undulatus Asperatus", translating as "roughened wave" in Latin. It was sent in by Weather & Radar user Gruffalo Griffin.

These clouds are part of a relatively new classification category, proposed back in 2009 by Gavin Pretor-Pinney of the Cloud Appreciation Society.

They form when there is instability in the atmosphere aloft, but relatively stable air at the surface. They have a well-defined structure and often look similar to rough ocean waves from below. After all, the atmosphere is fluid.

As the air moves up and down it creates long, rippling waves, which in turn produce dramatic visuals of the sky.